Playwright of some import once (5)
I believe the answer is:
orton
'playwright' is the definition.
(US playwright Joe Orton)
'some import once' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'ORTON' is hidden within 'import once'.
'of' acts as a link.
(Other definitions for orton that I've seen before include "Writer" , "British dramatist Joe, noted for black comedies" , "Joe -, dramatist (Entertaining Mr Sloane)" , "Joe -, English playwright" , "Controversial playwright" .)